<script type="text/javascript">
			function unique(arr){
					var hash=[];
					hash[arr[0]]=1;
					for (var i=1;i<arr.length ;i++ )
					{
						if(hash[arr[i]]===undefined){
							hash[arr[i]]=1
						}
					}

					var keys=[],i=0;
					for (keys[i++] in hash);
					console.log(keys);
					
			}

			console.time('unique');
			unique([20,50,20,40,50,10,20]);
			console.timeEnd('unique');
			
	</script>